1. Field of the Invention
This invention relates to a filter device, more particularly to a filter device for an aquatic tank to purify water therein.
2. Description of the Related Art
An aquatic tank generally has a filter device to purify water therein. Referring to FIG. 1, a conventional filter device (A) has a one-piece casing (a1) formed with a water entrance port (a2) and a water exhaust port (a3). The filter device (A) has a pumping unit and a filter medium provided with activated carbon mounted in the casing (a1). Since the filter device (A) has a limited filtering effect, another filter device with a larger filtering capacity is necessary when a larger aquatic tank is used.